Downhole casing-casing annulus sealant injection

Abstract

A downhole sealant injection system includes a first casing configured to be positioned in a wellbore and a second casing configured to be positioned in the wellbore within the first casing. Cement at least partially fills an annulus between the interior of the first casing and the exterior of the second casing. A first sealant injection tool is configured to be attached to the exterior of the second casing, and is positioned at a downhole location and within an annulus between the interior of the first casing and the exterior of the second casing. The sealant injection tool includes a plurality of nozzles configured to inject sealant into voids within the cement in the annulus between the interior of the first casing and the exterior of the second casing.

What is claimed is: 
     
       1. A downhole sealant injection system, comprising
 a first casing configured to be positioned in a wellbore; 
 a second casing configured to be positioned in the wellbore and to be cemented within the first casing such that cement at least partially fills an annulus between the interior of the first casing and the exterior of the second casing; 
 a first sealant injection tool configured to be attached to the exterior of the second casing, the first sealant injection tool configured to be positioned at a downhole location and within the annulus between the interior of the first casing and the exterior of the second casing, wherein the sealant injection tool comprises a plurality of nozzles configured to inject sealant into voids within the cement in the annulus between the interior of the first casing and the exterior of the second casing after the second casing has been cemented within the first casing. 
 
     
     
       2. The downhole sealant injection system of  claim 1 , wherein at least a portion of the plurality of nozzles are defined in at least one of a plurality of centralizer arms. 
     
     
       3. The downhole sealant injection system of  claim 2 , wherein the centralizer arms are hollow, and wherein an interior of the nozzles is fluidically connected to an interior of the centralizer arms. 
     
     
       4. The downhole sealant injection system of  claim 1 , further comprising a second sealant injection tool attached to the exterior of the second casing, the second sealant injection tool comprising a second plurality of nozzles configured to inject sealant into voids within the cement in the annulus between the interior of the first casing and the exterior of the second casing. 
     
     
       5. The downhole sealant injection system of  claim 1 , further comprising a first control line configured to flow sealant from a surface control system to the first sealant injection tool. 
     
     
       6. The downhole sealant injection system of  claim 5 , further comprising a second control line configured to flow sealant from the surface control system to the second sealant injection tool. 
     
     
       7. The downhole sealant injection system of  claim 1 , wherein the nozzles comprise burst discs configured to flow sealant upon an exceedance of a burst pressure. 
     
     
       8. The downhole sealant injection system of  claim 1 , wherein the sealant comprises a resin. 
     
     
       9. A sealant injection tool, comprising:
 clamps configured to be attached to the exterior of a casing, the casing configured to be placed within a wellbore; 
 a plurality of centralizer arms attached to the clamps and extending radially outward from the casing; 
 a plurality of nozzles defined in the centralizer arms, the plurality of nozzles configured to inject sealant into a space exterior of the casing within the wellbore. 
 
     
     
       10. The sealant injection tool of  claim 9 , wherein the centralizer arms are hollow, and wherein an interior of the nozzles is fluidically connected to an interior of the centralizer arms. 
     
     
       11. The sealant injection tool of  claim 9 , wherein the nozzles comprise burst discs configured to flow sealant upon an exceedance of a burst pressure. 
     
     
       12. The sealant injection tool of  claim 9 , wherein a first subset of the plurality of nozzles points outward away from the casing and a second subset of the plurality of nozzles points inward towards the casing. 
     
     
       13. The sealant injection tool of  claim 9 , wherein the sealant comprises a resin. 
     
     
       14. A method of sealing an annulus between a first casing and a second casing, the first casing positioned within a wellbore, the method comprising:
 attaching a first sealant injection tool to the exterior of the second casing, the sealant injection tool comprising a plurality of nozzles; 
 lowering the second casing and the sealant injection tool into the wellbore within the first casing; 
 cementing the second casing within the first casing by flowing cement into the [an] annulus between the interior of the first casing and the exterior of the second casing; and 
 injecting, after the second casing has been cemented within the first casing, sealant from the nozzles, the sealant filling voids within the cement in the annulus between the interior of the first casing and the exterior of the second casing. 
 
     
     
       15. The method of  claim 14 , wherein a downhole end of a first control line is configured to be fluidically connected to the first sealant injection tool, and further comprising fluidically connecting an uphole end of the first control line to a surface control system. 
     
     
       16. The method of  claim 15 , further comprising flowing sealant from the surface control system through the first control line. 
     
     
       17. The method of  claim 14 , further comprising attaching a second sealant injection tool to the exterior of the second casing, the second sealant injection tool comprising a second plurality of nozzles configured to inject sealant into voids within the cement in the annulus between the interior of the first casing and the exterior of the second casing. 
     
     
       18. The method of  claim 17 , wherein a downhole end of a second control line is configured to fluidically connect to the second sealant injection tool, and further comprising fluidically connecting an uphole end of the second control line to a surface control system. 
     
     
       19. The method of  claim 14 , wherein the nozzles comprise burst discs, and further comprising applying pressure to the first control line sufficient to burst the burst discs. 
     
     
       20. The method of  claim 14 , wherein the sealant comprises a resin.